Mechanical pencil



Feb. 6, 1934. A. N. LUNGREN MECHANICAL PENCIL Filed Nov. 5, 1932 Patented Feb. 6,. 1934,y

' UNITED STATES PATENT oI-Frce The Wahl Company, Ghi

of Delaware cago, lll., a corporation Application November 5, 1932. Serial No. 641,418

Claims.

This invention relates to mechanical pencils, and is applicable with particular advantage in mechanical pencils of the so-called detachable tip type, wherein the lead in writing position is 5 retained in a tip portion of the pencil which is rotatable with respect to the pencil barrel forthe rtiurpose of feeding the lead to the Writing posiion.

One object of the invention is the provision oi 9 a construction which will be effective to hold the Y detachable tip portion of the pencil securely against wabbling with respect to the barrel, and at the same time permit rota adjustment of the tip with respect to the ybarrel for the pur- 5 pose of feeding the lead, andallow removal .of the tip from the barrel, when desired, for the purpose of inserting new lead sticks.`

Another object of the invention is the provision of a mechanical pencil of the detachable 2@ tip type which may be manufactured very economically and which will be very sturdy and durable.

Yet another object is the provision of a mechanical pencil construction in which the metal parts are of very simple character and susceptible of being formed very easily. A I

Yet another object of the invention is the provision oi a construction ior detachable tip pencils which will be eective to prevent the binding or 3g, sticking together of the parts winch are intended to be relatively movable for the purpose of replenishing or feeding the lead.

Other and further objects of the invention will. be pointed out or indicated hereinafter, or will be 'apparent upon an understanding of the invention or its employment in use.

- For the purpose of aiding in an explanation of the invention I show in the accompanying drawing forming a part of this specification, and here- 4U inafter described, certain embodiments of it, but it is to be understood that these examples are presented merely by way of illustration of the essential features of the invention, and hence are not to be construed in any fashion calculated to limit the appended claims short of the true and most comprehensive scope of the invention in the art.

in said drawing,

Fig. 1 is a part longitudinal sectional view of a mechanical pencil construction embodying the invention;

Fig; 2 is a cross section. on substantially line 2-2 of Fig. 1,; Fig. 3 is a cross section 3-3 of Fig. 1;

on substantially line (Cl. 1Z0-18) A Fig; 4 is an elevational view of a holding element;

Fig. 5 is a broken or part longitudinal sectional view of a mechanical pencil barrel embodying' a modified form of the invention;

Fig. 6 is a cross .section onr substantially line 6-6 of Fig. 5; f

Fig. 7 is a perspective view of an alternative form of holding element; and L;

Fig. 8 is a perspective view of a third form of 65 holding element.

In view of the comparatively simple character of the construction, it is believed that an understanding of the invention may be had most quickly by a considera-tion of these various illustrative embodiments in detail. v

Referring first to the construction illustrated in Figs. 1, 2 and 3, it will be understood that the reference numeral 10 designates the barrel or shaft portion of the pencil, same being provided withY an axially extending non-circular guideway 1l opening at its lower end into an axially aligned cavity 12 of circular contour, which cavity communicates at its lower end with a bore 14 of considerably larger diameter. The fbore 14 extends 80 tothe lower end of the barrel.

Closely tted in the bore 14 is aholding element made up of a plurality of disk-like sections l5 formed with central apertures disposed co- 'aXially with the cavity 12. This holding element 85 `is of elastic or resilient character, and in the construction here referred to may be made of cork or other material of similar character.

Also tted in the bore 14 are the rigid spacer or centering members 16 and 17, same being 90 spaced from each other a substantial distance longitudinally of the barrel. As here shown, the i centering element 16 is adjacentl the upperend of the bore 14, and the element 17 occupies the lower end of the bore. These centering elements Y have central apertures aligning axially with the cavity 12. The member 17 isknurled at its periphery so that it bites into the material of the barrel invsuch fashion that it is held securely in place and serves to confine the portions 15 and 100 16 in the bore. The portions 15 and 16 preferably are arranged in close abutment with oney an'- other, and the' elastic material of the members 15 may be held under some compression. by the member17.

The centering member 17 is provided at its lower end with an outwardly extending flange n 17 which abuts against the lower end of the barrel, the lower surface of the member 17 extending normal to the axis of the barrel.

Thede 'ienpeomprisesoieed'guido tube 18 and a tapering sheath portion 19 which,"

encompasses the lead guide tube for a portion of its length, said sheath being permanently -connected to the lead guide .tube and terminating at a slight distance above the lower end thereof. At its upper' end the surface of the sheath ex-f tends approximately normal to the axis of the lead guide tube and is of approximately tlie same diameter as the lower end of thebarrel.

- "The lower end of the lead guide tube is cleft y at 20 and swaged inwardly, so that the bore of its terminal portion .is somewhat reduced in size and of somewhat smaller cross-sectional area 1|V than the cross section of the lead stick which it is contemplated to be employed in the pencil. At its upper -end the lead guide tube is swaged inwardly somewhat, and the bore of the swaged in the central apertures of the centering elee' ments 16 and 17. The form and size of the axial aperture of the holding element, on the other hand, are such that the intrusion of the lead 'guide tube therein will produce some elastic compression or deformation ofthe material of the holding element. As a consequence, the holding element will grip the lead guide tube with an elastic pressure effective to retain the tip assembly in position, yet permit its being' withdrawn from thebarrel or rotated with respect thereto upon application of requisite force.

sures a good grip on feed tube 18 even though thelattermayvaryinsizetbroughtherange of commercial tolerances. Thus interchangeability is assured and manufacture facilitated.

In use of the pencil in writing, the tip assembly is subjected to lateral pressure tending to press it out of alignment with the barrel. Such displacement of the tip assembly is definitely prevented, however, by the centering members 16 and 17 which afford the lead guide tube xed points of support atlocations spacedF longitudinally thereof. The bearing of the upper end of the sheath 19 against the lower surface of the member 17 likewise resists lateral displacement of the lead guide tube. and although the lead roi-ds on additional stinening reinforcement :or

the portion thereof below the end of the barrel.'

The segments formed at the lower end of the lead o guide tube by the'slotting thereof admit of slight outward displacement. whereby` they are ten.

sioned so as toexert a resilient gripping action ,l upon a suitable lead stickin the bore, thereby, i to hold it-s'ecurely-against turning or dropping Loue elastic nature ofthe washers 15 also in.

guide tube is itself quite stiif, the sheath 19 af- 'inthebal'relbol'e Not only does the cooperative arrangement of` ture is so formed that a portion extends slightly inwardly beyond the line of the walls of the axial apertures of the centering members 16 and17,asillustratedinFig.3. InFig.4is illustrated one of various forns in which the 30 holding element may be made in order to produce this eifect. By forming the holding element of a plurality of the sections 15, a distributed arrangement of these inwardly projecting portions aboutthe lead guide tube may be made. Upon the insertion of the upper end of the lead guide tube into the lower end of the barrel, its reduced I upper end will enter between these inwardly projecting portions of the holding element, sothat they willbe wedged outwardly by the intrusion 9( of the lead guide tube, thus permitting the latter to be moved to position smoothly without sheare ing=oif or abrading the contacting portions of the holding element. When the tip assembly is1 in seated position, its upper end portion occupies V the cavity l2, and the spline 22 of the propeller is accommodated in the spline guideway 11 with suillcient looseness or .play to accommodate any slight misalignment of said guideway and the lead guide tube, thereby avoiding any springing or cramping of the propeller and the subjecting of the leady guide tube to any eccentric pressure therefrom.

i In Figs. 5 and 6 is illustrated ra modified form of barrel construction which permits the use of tubing having a straight uniform bore. In this construction the barrel is/formed ironia' section of straight tubing 25 and inserted core portion 26 which is ressed into the bore of the tube section with tight non-rotatable it. This core no is formed with the axial spline guideway 11' and with the cavity 12' at its'lower end. The centerving members 1c' and 17' are positioned in the i f tube extending into the cavity 12' when the tip 120 assembly is in position.

The upper end of the spline guideway is closed or covered by a plug 27, and aI portion of the tube bore thereabove allords a magazine 28 for lead sticks. This magazine is closed at its upper end 'by an eraser 29 audits holding ferrule 30; re-

movably seated in a slightly counterbored portion of the upper end of the barrel, and a removable cap 31 is iltted tothe upper end of the barrel to housethe eraser, Y

The holding element may be made in any of various forms which vary in' specic features from those above described. For example, in the fbrmvillustrated in Fig. 7, it is made up of complementary segments 32, of cork or similar elastic frictionall material, which segments, when as- Y sembled in complementary relationship, iit snugly 'aiford the axial passage for accommodation of e lead guide tube.

The holding element illustrated in Fig. 8 is 140 thev lead guide tube with the entering mma formed from a sheet of resilient metal shaped to prevent wobbling between the tip assembly' and tully. under compression if desired, in the 5* the barrel, but also prevents crushing or 'perb0re.,'nd having the resilient-portions 34 70 marient distortion of the elastic holding e1ement, f"mnsd t0 accommodate the lead guide tube as itimposesa definite limit tothe pressure which beim them' @d t0 clasp' it with resilient PreS- may be imparted to the holding element bythe' sure. Holding elements'ofthe nature of those leadguidetube. llhistratedinl'igalandwouldbearrangedin g Inorderthattheelasticholdingelementmay the rebetweenthespacedcentering' "u mnu-1y srt the leed guide mbe. arma w and r1, and would function in oon operative relationship therewith as above described.

Injtheoperation of the pencil, for insertion of ajleadstick, the tip assembly is withdrawn from thebarrel, the plunger 21'unscrewed and removed from the lead guide tube, and a lead stick of suitable size inserted into the latter through the opening at'its upper end. The propeller is then reinserted in the upper end of the lead guide tube and its thread turned into the thread of the latter for a short distance.` The tip assembly is then remounted on the barrel, the. projecting portion of the plunger being inserted into the spline guideway and the lead guide tube being inserted through the axial apertures of the centering members and the holding element until the sheath 19 abuts the member 17. Thenj upon relative rotation of the barrel and tip in the proper direction, the propeller will be screwed further into the lead guide tube, and its lower end will abut the upper end of the lead stick in the latter and propel l the lead stick longitudinally toward the lower eid (sa Lil of the tip. i

The member 17 with its ange 1'1a forms a neat and wear-resisting finish for the lower end,of the barrel, Yand by extending and rounding the `periphery of the .flange somewhat beyond thev portion having a lead guide tube insertable lon' gitudinally into the barrel, centering members carried by the barrel for cooperation with the lead guide tube to hold it in axial alignment with the barrel, and a` holding element adapted to engage the lead guide tube intermediate the centering members to hold it in place by friction, yet permit its rotation and withdrawal upon application of sufficient force.

2. In a mechanical pencil, the combination as specified in claim 1 and wherein one of the centering members is at the lower end of the barrel and the other spaced apart therefrom longitudirially of the barrel and the holding element is interposed between them.y

3. In a mechanical pencil, the combination specified in claim 1 and wherein the centering members are provided with axial apertures slidably receiving the lead guide tube and the holding element has an elastic portion arranged for cooperation with the lead guide tube.

4. In a mechanical pencil, in combination, a barrel affording an opening at its lower end, a tip portion having an axial tube insertable longitudinally into the lower end of the barrel, centering means in the barrel for cooperation with the tube at points spaced apart a substantial proportion of its length to hold it in axial alignment with the barrel, and a holding element in the barrel above the lower terminals of the centering means adapted to exert yielding pressure on the tube to restrain it frictionally against movement yet permit its rotation within the barrel and its withdrawal from l.the barrel upon application of requisite force.

5. In a mechanical'pencil, the combinationas specied in claim 4 and including a sheath on the lower portion of the tube and having its `tion of the -barrel each provided with an axial yielding pressure on an area of the tube interupper end for abutment with the lower end of the barrel.' y 6. In a mechanical pencil, the combination-as specied in claim 1 and including alead propeller i movable longitudinally in the leadguide tube by relative rotation of the tip member and barrel.

' '7. In a mechanical pencil, in combination, a

barrel affording an opening at its lower end,

rigid centering members in the lower end poropening and which openings are inalignment, a tip member having an upwardly extending tube adapted to iit slidably in said openings, and a holding element in the barrel adaptedto exert mediate the centering members.

8. In a mechanical pencil, in combination, a barrel affording an axial opening at its lower end, a tip member having an upwardly extending tube movable longitudinally through said opening, rigid means inthe barrel for holding the tube against movement laterally thereinp and holding means in the barrel for exerting resilient pressure on peripheral portions ofthe tube within the barrel.

9.' In a mechanical pencil, the combination as speciiied in claim 8 and wherein said holding means comprises an annular resilient member constrained by the barrel and encompassing the tube and frictionally engaging peripheral portions" thereof.

10. In a mechanical pencil, in combination, a barrel affording an axial bore, a centering memj l ber fixed to the barrel at its lower end and having an axial aperture, a tip member having a projecting tube portion adapted to fit slidably in said aperture and extend into the bore of the barrel, a resilient holding element in the boreof the barrel and having frictional engagement with peripheral portions of said tube, said tip member- 315 including a portion extending outwardly from said tube and adapted for abutment vwith the lower surface of said centering member, and the centering member having an outwardly extending' ange abutting'the lower end of the barrel and 120 projecting slightly beyond the periphery of thev abutting portion of the tip member.

-1l. In a mechanical pencil, in combination, a barrel having an axial bore, a rigid centering member xed in the bore and affording an axial aperture, an elastic ring arranged in the bore and provided with an axial aperture, and a tip member having a tube extending axially therefrom and adapted for sliding t in the aperture of the centering member and.for frictional intrusion in the aperture of the ring to induce elastic compression of portions of the ring, the tip member having a portion extending outwardly from the tube to limit the insertion of the latter into the barrel. v

12. In a mechanical pencil, a tubular barrel, a

lrigid centering. member ixed in the lower end as to retain it in place yet permit its withdrawal and rotation upon application of suilicient force. 13. lIn a mechanical pencil having a barrel and removable tip tube, a tip-retainingA device comm prising an apertured cork member retained in the f barrel and adapted to receive and exert trictional retaining pressure on the tip tube.

14. In a mechanical pencil, a tip-retaining de- 'vice as specied in claim 13 and including also a rigid centering member retained in the barrel in association with' said apertured cork memberl and tube adapted for guiding cooperation with the tip lno isa 

